The antiglare and antireflection film has a function of reducing the reflectance using the scattering of light by surface protrusions and the thin film interference and in an image display device such as cathode ray tube display device (CRT), plasma display panel (PDP), electroluminescence display (ELD) and liquid crystal display device (LCD), this film is generally disposed on the outermost surface of a display so as to prevent the reduction of contrast due to reflection of external light, or prevent the entering by reflection of an image.
As for the design of surface shape of the antiglare layer, JP-A-8-309910 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) discloses a technique for attaining both antiglare property and transmittance by setting the thickness of the antiglare hard coat layer to 50 to 90% of the average particle size of synthetic resin particles.
In recent years, techniques for improving the image display quality, such as wide view angle of liquid crystal display, rapid response and high refinement, are making a progress. One of the image display qualities is “good black without cloudiness in the black display when the power source is ON”, namely, “how black the black can be displayed”, and this is found to be very important for satisfying needs from users.
The antiglare techniques of using the surface scattering by surface protrusions for preventing the reduction in contrast due to reflection of external light or preventing the reflection of an image are accompanied by such problems that white blurring occurs or black is loosened. In using the antiglare and antireflection film, these problems must be solved.
Accordingly, in designing the antiglare layer, the surface shape must be designed to establish both antireflection and good black without cloudiness, but the above-described technique described in JP-A-8-309910 cannot satisfy this requirement.
In recent years, the demand for high refinement, namely, high image quality of a liquid crystal display is particularly very strong in addition to the wide view angle and rapid response. The high refinement can be realized by the formation of microsize liquid crystal cells, however, when the cell size becomes small, the surface protrusion of the antiglare and antireflection film acts as a fine lens and by a so-called “lens effect”, the light transmitted through the antiglare and antireflection film and reached an eye of a user is dispersed in the brightness, namely, “glaring” is caused, as a result, the display quality is disadvantageously deteriorated.
To solve this problem, JP-A-11-95012, JP-A-11-305010, JP-A-11-326608, JP-A-2000-338310, JP-A-2001-154004, JP-A-2000-75133 and JP-A-2000-227509 disclose a method where a difference is given between the refractive index of an antiglare layer and the refractive index of a light-transmissive particle contained in the layer, so that the light passing through the antiglare layer is internally scattered and thereby, occurrence of glaring is prevented.
However, in the region of ultrahigh refinement, for example, of 133 ppi (133 pixels/inch), the simple method using internal scattering described in those patent publications encounters a new problem such as blurring of letters or mixing of colors due to use of internal scattering, though the glaring can be improved. Thus, both the improvement of glaring and the prevention of blurring of letters/mixing of colors cannot be attained at the same time.